The present invention relates to agricultural spraying systems, and, in particular, to a modular broadcast/strip application system whereby strip application is achieved with a relatively high back-pressure conversion assembly.
Prior to the present invention, various research and field trials have demonstrated that row crop yields can be increased by applying various liquid fertilizers which may include various proportions of nitrogen, phosphorous and potassium in concentrated bands or strips relative to the row crops rather than by applying the same amount of material in a broadcast fashion over the entire area between row crops. While strip application may be performed prior to, during, or subsequent to planting and with various desired spacings relative to the row crops, it generally serves to make the applied treatment materials more rapidly available to the growing row crops. The availability of nutrients and increased yields, in turn, have however become more important as the costs for such treatment materials have risen. For more information with respect to such application techniques, attention is directed to Chapter 20 of the Liquid Fertilizer Manual of the National Fertilizer Solutions Association and to various product literature from the various suppliers of chemicals for row crops (e.g. a publication entitled Improving Per Pound Efficiency by Positive Placement published by Allied Chemical Company).
While surface band and strip application techniques have been known for some time, application systems are more typically designed for broadcast spraying and which is the more forgiving of operator and equipment error. Single purpose systems have been designed though for strip application. In either case, the resulting special purpose systems require an operator to maintain separate pieces of equipment which is not economical.
The present invention, therefore, is directed to a multi-purpose spray system and in particular to a broadcast spray system that is easily converted to a strip spray system via the coupling of individual strip spray nozzle assemblies to desired ones of the outlet parts of the broadcast system. In this regard, the spray nozzles of a broadcast spray system are typically spaced apart from one another on the order of 60 inches. For strip application, however, it is desirable to space the nozzles on the order of 15, 20 or 30 inches apart. Assuming therefore that it is desired to apply the same amount of material with more nozzles, the flow rate per nozzle must be reduced on the order of one-fourth, one-third or one-half for the above outlet port spacing. While this end can be achieved by reducing the aperture size of the orifice for each nozzle, such a reduction introduces problems that are not advantageous to a convertible system.
In particular, attendant with any decrease in the aperture size of the orifices for strip application are concerns with respect to pressure and particulate size, since often times the liquids that are sprayed are comprised of mixtures that contain suspended solids. Therefore too small an aperture can result in blockage, should various of the suspended particles become lodged at the orifice opening. The present invention, therefore seeks to minimize clogging sensitivity by using relatively large orifices having apertures on the order of 0.20 inches in diameter for strip application. Such orifices however introduce concerns with respect to pressure.
Pressure is a concern in that the pressure requirements of a broadcast system require less regulation than for a strip system. Specifically, due to the fewer number of nozzles for a broadcast system, a single control can typically maintain equivalent pressures at each outlet port and nozzle and thereby achieve a uniform flow rate at each nozzle. However, by converting a broadcast system to a strip system by increasing the number of nozzles and at the same time increasing the aperture size and reducing the pressure at each nozzle, variations in pressure from nozzle to nozzle can result and produce disparities in flow rates, which otherwise are not encountered at the higher pressures and fewer nozzles of a broadcast system. Therefore it is a primary object of the present invention to enable the conversion of a broadcast system to a strip application system having substantially uniform pressures at each strip nozzle and wherein the system will accommodate various types of liquid suspension as well as totally dissolved solutions.
It is a further object of the present invention to enable a modular system capable of high speed application with output metering orifices that also shape the flow streams at each nozzle into narrow-high velocity solid streams.
It is another object of the present invention to minimize or eliminate the sensitivity to viscosity variations in mixed fertilizers and maintain a predictable flow rate.
It is a still further object of the present invention to enable a convertible system wherein the flow rate at each outlet nozzle is regulated by a plurality of pressure adjusting series/parallel orifices.
These objects and still others will, however, become more apparent upon a reading of the following description with respect to the following drawings.